I've got a stockpile of 10 quarts of 10W-30 synthetic motor oil left over from my previous vehicle.

You think there is any problem is using this in the 3G TL?

What could be the problem, if any?

 

It is always good to use the recomended oil for an engine. Though it would not be tragedy if you used this oil the 5W-20 oil has the best viscosity for use on this engine. So in theory it is not as good for your engine to run on that oil, how much of a real difference it makes I am not sure.

 

I think I would wait for warmer (summer) temperatures to use it .

 

No problem using it...just that the extra viscosity is unnecessary. Only thing you may experience is a slight power loss and/or a slight reduction in fuel efficiency due to the thicker oil.

 

My experience...


22-24 mpg with 5w30.
23-26 with 5w20

This was measured with mixed driving, same route, back and forth to work.